Portable, self-contained data collection systems and methods

ABSTRACT

A portable self-contained data collection system for measuring and collecting vibration data from machines includes an accelerometer which is coupled to the analog input of a data acquisition card. The data acquisition card samples and digitizes the analog signal to produce a time domain digital signal. The data acquisition card output is coupled to a battery-powered portable computer. The battery-powered portable computer includes a database having machine identifications and associated measurement parameters. The portable computer processes the time domain digital signal according to the measurement parameters associated with a selected machine identification, and produces a frequency domain digital signal by performing a Fast Fourier Transform and other digital signal processing operations. The frequency domain signal is also analyzed in the portable computer to produce predictive maintenance information. A power supply for supplying power to the accelerometer is also included. The accelerometer power supply electrically and mechanically couples the accelerometer to the data acquisition card. It supplies power to the accelerometer when the data acquisition card is activated. The portable self-contained data collection system can be used to measure and collect vibration data from machines and to analyze this data to produce predictive maintenance information.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of application Ser. No.08/526,981, filed Sep. 12, 1995.

FIELD OF THE INVENTION

[0002] This invention relates to predictive maintenance systems andmethods, and more particularly to computer-based data collection systemsand methods for measuring and collecting vibration data from machines.

BACKGROUND OF THE INVENTION

[0003] Data collection systems and methods are now widely used formeasuring and collecting vibration data from machines, for predictivemaintenance purposes. Data collection systems typically include twomajor components: a portable data collector and a host computer. Theportable data collector is typically a dedicated instrument to whichaccelerometers can be coupled, and which stores accelerometer-basedvibration data for a machine. An example of a state-of-the-art datacollector is the EMONITOR® dataline™ data collector marketed by EntekScientific Corporation, assignee of the present application. TheEMONITOR® dataline™ data collector is described in a manual entitled“EMONITOR® for Windows EMONITOR® dataline™ (U.S.) Data Collector User'sGuide, First Edition 1995”, Manual No. EEW2501A, published by EntekScientific Corporation, the disclosure of which is incorporated hereinby reference.

[0004] The host computer is typically a standard PC-based computer whichruns predictive maintenance data management and analysis softwarethereon. The host software allows a user to set up a database to modelthe machinery for which vibration data is to be obtained. The softwareallows lists of machines to be set up for data collection. Each listincludes a set of measurement parameters that control where and how totake and store a measurement. The host software allows one or more liststo be loaded into the data collector for collection. The user then takesthe data collector to a machine to be measured, accesses the measurementparameters for that machine, and collects and stores vibration and otherinformation. After collection, the data is unloaded from the datacollector to the host. The host software then allows the data to beanalyzed. Reports can be generated, including reports of measurementsthat exceed alarms. Graphical displays of the data can be produced,including trend, spectrum, frequency trend, time waveform and spectrummap plots.

[0005] An example of data management and analysis host software isEMONITOR® for Windows, which is marketed by Entek ScientificCorporation, the assignee of the present invention. The EMONITOR® forWindows software is described in a manual entitled “EMONITOR® forWindows User's Guide, Second Edition 1994”, Manual No. EEW0002B,published by Entek Scientific Corporation, the disclosure of which isincorporated herein by reference.

[0006] In state-of-the-art manufacturing environments, the capitalinvestment in machinery can be staggering. Accordingly, there is a greatneed for predictive maintenance to prevent machine breakdowns andincrease reliability. Moreover, with “just in time” manufacturingrequirements, predictive maintenance becomes even more critical toeliminate machine down time. Accordingly, there is a great need for datacollection systems and methods.

[0007] Unfortunately, the high cost of data collection systems is oftena barrier to their widespread use. The high cost is in part related tothe use of special purpose hardware and software in the data collector.In addition to high cost, the use of special purpose hardware andsoftware limits the flexibility of the data collector and makes itdifficult to update and improve the data collector. Although portablecomputers, laptop computers, pen-based computers, palmtop computers andPersonal Digital Assistants (PDA) have become widely available, theyhave not yet made a significant impact on data collectors. See forexample, the publication in Automatic ID News, April 1995, entitled “BeReady for Technology Leap at the End of the Century: Three Non-ADCDevelopments to Springboard Automatic Data Capture Growth”. See also thepublication in Maintenance, January/February 1995, by Billson et al.entitled “Portable Pen Computers—An Essential Tool for the MobileMaintenance Engineer”.

SUMMARY OF THE INVENTION

[0008] The present invention is a portable, self-contained datacollection system for measuring and collecting vibration data frommachines. The system includes an accelerometer including a motionsensitive transducer and an accelerometer output. The accelerometer iscoupled to a machine to produce an analog signal at the accelerometeroutput. The system also includes a data acquisition card having ananalog input and a digital output. The accelerometer output iselectrically coupled to the analog input. As used herein, electricalcoupling includes wireless, optical or conventional wire coupling. Thedata acquisition card samples and digitizes the analog signal to producea time domain digital signal, i.e. a sampled and digitized series ofvoltage versus time points, at the digital output. The system alsoincludes a battery-powered portable computer such as a pen-basedcomputer, which includes an expansion slot. The data acquisition carddigital output is electrically and mechanically connected to theexpansion slot.

[0009] The battery-powered portable computer also includes a databasehaving machine identifications and associated measurement parameters.User input means such as a pen allows user selection of a machineidentification for measurement. The portable computer also includessignal processing means for processing the time domain digital signalaccording to the measurement parameters associated with the selectedmachine identification. Preferably, the signal processing meansprocesses the time domain digital signal to produce a frequency domaindigital signal by performing a Fast Fourier Transform (FFT), wavelet orother digital signal processing operations. Finally, the battery-poweredportable computer also preferably includes signal analyzing means foranalyzing the frequency domain digital signal to produce predictivemaintenance information such as spectral distribution. The time domaindigital signal can also be analyzed to produce crest factor and otherpredictive maintenance information.

[0010] A data collection system according to the present invention usesa standard portable computer such as a pen-based computer and a standarddata acquisition card such as a PCMCIA sound card, to provide portableself-contained hardware for data collection and analysis. The machinedatabase, signal processing means and signal analyzing means arepreferably implemented using software modules which execute on theportable computer. The machine database and the signal analyzingsoftware may be provided using EMONITOR® for Windows or other predictivemaintenance software on the portable computer. Signal processingsoftware may be provided by conventional digital signal processingsoftware which provides digital filtering, integration from accelerationto velocity or displacement units, Fast Fourier Transform or othermathematical functions, and averaging. Accordingly, a low costself-contained data collection system is provided.

[0011] It will be understood that since the portable data collectionsystem includes a database, signal processing software and signalanalyzing software therein, a host computer connection is not requiredfor operation. Rather, all predictive maintenance operations may beperformed using only the portable self-contained data collection system.However, it will also be understood by those having skill in the artthat the portable self-contained data collection system can be used aspart of a networked data collection system wherein the portable computerincludes transmitting means for transmitting at least one of the machineidentifications, the measurement parameters, the time domain digitalsignal, the frequency domain digital signal or the predictivemaintenance information to a second computer. The second computer maystore this data for distribution to other users and the second computeror other users may also perform one or more of the processing functionsof the portable data collector. The transmitting means is preferablywireless, such as a radio frequency (RF) transmitter. However,transmission may also be accomplished by uploading information toanother computer using conventional wire communications.

[0012] According to another aspect of the present invention, theportable self-contained data collection system also includes a powersupply for supplying power to the accelerometer. In particular,conventional portable computers do not provide sufficient power for anaccelerometer, which typically requires 24V at 2 mA. According to theinvention, an accelerometer power supply electrically and mechanicallycouples the accelerometer output to the data acquisition card analoginput. The accelerometer power supply is preferably responsive to thedata acquisition card for supplying power to the accelerometer when thedata acquisition card is activated, and for deactivating when the dataacquisition card is deactivated.

[0013] In particular, the accelerometer power supply includes a powersupply housing and an accelerometer battery power supply in the powersupply housing which provides sufficient power for an accelerometer.Output means including an output connector electrically and mechanicallyconnects the accelerometer battery power supply to an accelerometer andreceives accelerometer signals from the accelerometer. Input meansincluding an input connector electrically and mechanically connects theaccelerometer battery power supply to an external device, preferably theanalog input of a data acquisition card. The input means receives acontrol signal from the external device, and also passes theaccelerometer signals to the external device. The accelerometer batterypower supply is responsive to the control signal, to activate theaccelerometer battery power supply to supply battery power for anaccelerometer to the output connector. In the absence of the controlsignal, the accelerometer battery power supply is deactivated.Preferably, the accelerometer battery power supply will pass signalsfrom the output means to the external device in the absence of thecontrol signal, so that non-powered transducers can be used.

[0014] When the accelerometer power supply is included, the portableself-contained data collection system includes three hardwarecomponents: a portable computer, a data acquisition card and anaccelerometer power supply. The portable computer includes a portablecomputer housing, a portable computer battery power supply within theportable computer housing to supply power to the portable computer, andan expansion slot in the portable computer housing. The data acquisitioncard is mechanically and electrically coupled to the expansion slot. Theaccelerometer power supply includes a power supply housing, and anaccelerometer battery power supply within the power supply housing whichprovides sufficient power for an accelerometer. The accelerometer powersupply is electrically and mechanically coupled to the data acquisitioncard and the accelerometer is electrically and mechanically coupled tothe accelerometer power supply. The portable computer, data acquisitioncard and accelerometer power supply may be packaged in a ruggedizedcarrying case. The portable computer executes software including adatabase including machine identifications and measurement parameters,signal processing software for processing accelerometer signals andsignal analyzing software for analyzing the processed signal to producepredictive maintenance information.

[0015] Data collection methods according to the present invention areused for measuring and collecting vibration data from machines, whereinthe following steps are all performed in a portable battery-poweredcomputer: A machine identification for measurement is selected. A timedomain accelerometer signal is processed according to measurementparameters associated with the selected machine identification toproduce a digital signal. The digital signal is analyzed to producepredictive maintenance information. If necessary, the processing step ispreceded by the step of sampling and digitizing an analog accelerometersignal to produce the time domain accelerometer signal. The machineidentifications, measurements, time domain signal, digital signal and/orpredictive maintenance information can be displayed on the portablebattery-powered computer. Portable self-contained data collectionsystems and methods are thereby provided. In addition, this informationcan be transferred to another computer.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]FIG. 1 illustrates a data collection system for collectingvibration data from machines according to the present invention.

[0017]FIG. 2 is a block diagram illustrating a data acquisition cardinterfaced to an operating system, database, signal processing means andsignal analyzing means implemented in a battery operated portablecomputer according to the present invention.

[0018]FIG. 3 is a block diagram illustrating signal processing means,including filtering, integration, fast Fourier transform, and averaging,for processing a time domain digital signal according to the presentinvention.

[0019]FIG. 4 is a block diagram illustrating a power supply for anaccelerometer according to the present invention.

[0020]FIGS. 5a-5 b illustrate data collection operations according tothe present invention.

[0021]FIGS. 6a-6 c are computer screen images illustrating a machineidentification selection according to the present invention.

[0022]FIG. 7 is a computer screen image illustrating signal analyzingaccording to the present invention.

[0023]FIG. 8 is a diagram illustrating a data collection systemimplemented in a battery operated portable computer linked to othercomputers in a computer network according to the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0024] The present invention now will be described more fullyhereinafter with reference to the accompanying drawings, in whichpreferred embodiments of the invention are shown. This invention may,however, be embodied in many different forms and should not be construedas limited to the embodiments set forth herein; rather, theseembodiments are provided so that this disclosure will be thorough andcomplete, and will fully convey the scope of the invention to thoseskilled in the art. Like numbers refer to like elements throughout.

[0025] Referring now to FIG. 1, data collection system 100 isillustrated, housed in a case 101. As shown, data collection system 100includes a battery-powered portable computer 110 mating to dataacquisition card 120, display means 130, user input means 140, powersupply 150, and accelerometer 160.

[0026] The construction of battery powered portable computer 110 iswell-known to those skilled in the art. Battery operated portablecomputers typically include a microprocessor, associated random accessmemory (RAM), nonvolatile data storage such as a hard disk drive, abattery power source and expansion slots designed to accommodate circuitboards electrically coupling the computer components to external devicessuch as keyboards, pens, mouses, transducers and displays. Theseexpansion slots typically accommodate standard form factor circuitcards, such as the industry-standard PCMCIA form factor cards used innotebook and laptop computers. For field uses, such as monitoring ofmachinery for predictive maintenance purposes, battery operated portablecomputer 110 may be mounted in a lightweight, rugged hand-held case 101,and user input means 140 may include a magnetic pen designed to operatewith a magnetically sensitive screen matrix. An example of a typicalbattery operated portable computer designed especially for field use isthe Fujitsu Stylistic 500, as described in Fujitsu brochure 58-0349-00B,the disclosure of which is incorporated herein by reference. Thiscomputer is referred to for purposes of explanation only, and it will beunderstood by those skilled in the art that the present invention may beused with other portable computers.

[0027] Data acquisition card 120 is an analog to digital (A/D) convertercard that mechanically and electrically couples data acquisition card120 to an expansion slot in battery powered portable computer 110,electrically connecting digital output 122 to battery operated portablecomputer 110. Data acquisition card 120 is electrically coupled toaccelerometer 160 at analog input 121. Typically, data acquisition card120 is a low-cost standard form factor sound card designed to receiveaudio frequency analog signals at analog input 121. An example of such asound card is the Magic Ram PCMCIA 16-bit audio adapter, which isdescribed in a manufacturer's data sheet entitled “PCMCIA 16-bit AudioAdapter,” the disclosure of which is incorporated herein by reference.This device is a standard PCMCIA form factor card that mates with aPCMCIA expansion slot. It will be understood by those skilled in the artthat a data acquisition card according to the present invention includesany A/D converter card capable of receiving analog inputs andtransmitting corresponding digital signals to a battery operatedportable computer through a digital communications port, such as anexpansion slot. It will also be understood by those skilled in the artthat the present invention may be used with a battery operated portablecomputer 110 which includes an analog input and associated internal A/D.

[0028] Accelerometer 160 produces an analog signal corresponding to theaccelerations experienced by a motion sensitive transducer includedtherein, and is electrically coupled to data acquisition card 120 byanalog input 121. The motion-sensitive transducer is typicallypiezoelectric and produces a voltage proportional to the acceleration ofthe transducer. The accelerometer includes means for coupling the motionsensitive transducer to a machine from which the user desires vibrationdata, such as a probe extension, screw or magnet attached to theaccelerometer structure. Examples of piezoelectric accelerometers may befound in Catalog QSG-200, published by Industrial MonitoringInstrumentation Division of PCB Piezotronics, Inc., the disclosure ofwhich is incorporated herein by reference. It will be understood bythose skilled in the art that the present invention may be used withother measurement devices producing analog output signals correspondingto accelerations, such as piezotransistor or variable resistanceaccelerometers.

[0029] Power supply 150 supplies electrical power to accelerometer 160,receives output signals from accelerometer 160, receives control signalsfrom data acquisition card 120, and conveys output signals fromaccelerometer 160 to data acquisition card 120. Power supply 150 ismechanically and electrically coupled to both accelerometer 160 and dataacquisition card 120.

[0030] Referring now to FIG. 2, a block diagram illustratesaccelerometer 160, data acquisition card 120 and user input means 140interfaced to an operating system 200, data collection interface 210,database 220, signal processing means 230 and signal analyzing means240. Operating system 210 is typically executive software that controlsdata collection interface 210, database 220, signal processing means230, signal analyzing means 240, and data acquisition card 120,responsive to commands received through user input means 140. Suchcommands may be to acquire or store data, or to perform filtering, timedomain analysis, or frequency domain analysis. An example of operatingsystem 200 is Entek Scientific Corporation's EMONITOR® for Windows datamanagement software, as described in “EMONITOR® for Windows User'sGuide, Second Edition 1994,” Manual No. EEW0002B, the disclosure ofwhich is incorporated herein by reference. This software is aWindows-based program that enables a user to perform databasemanipulation, data analysis or other operations via manipulation ofscreen icons. It will be understood by those skilled in the art that thepresent invention may be used, for example, with other operating systemsrunning in a Windows, DOS, or UNIX environment.

[0031] Database 220 comprises a plurality of machine identifications andassociated measurement parameters. Database 220 may have a hierarchical,relational or other structure and is typically organized according tological relationships between particular machines. An example of ahierarchical database structure is incorporated in Entek ScientificCorporation's EMONITOR® for Windows, as described in Chapters 4 and 5 of“EMONITOR® for Windows User's Guide, Second Edition 1994,” Manual No.EEW0002D. This database is a SQL database that organizes machineidentifications, and associates parameters such as machine location,signal processing parameters and previously measured data values withthese machine identifications. This database is referred to for purposesof explanation, and it will be understood by those skilled in the artthat the present invention may be used with other hierarchical ornon-hierarchical database structures, and may include variouscombinations of machine parameters.

[0032] Data collection interface 210 is preferably a software modulethat controls the operation of data acquisition card 120 and signalprocessing means 230 through operating system 200, although hardware orsoftware/hardware combinations may be employed. Upon commands from datacollection interface 210, data acquisition card 120 samples anddigitizes an analog signal 115 received from a accelerometer 160 andprovides a corresponding time domain digital signal 125, which isconveyed to signal processing means 230. In the embodiment of thepresent invention shown in FIG. 2, data collection interface 210 is asoftware module operating in conjunction with, for example, an operatingsystem such as EMONITOR® for Windows running in a Windows environment,and is conveniently accessed and controlled by user selection ofappropriate icons in a display window.

[0033] Although the combination of elements described in FIG. 2envisions data collection, database management and data analysisintegrated in a multitasking environment such as Windows, it will beunderstood by those skilled in the art that the present invention may bepracticed using other means of interfacing data acquisition card 120,signal processing means 230, signal analyzing means 240 and database220. For example, data collection interface 210 may be a standalonesoftware program capable of transferring data from data acquisition card120 to database 220 for subsequent data management, signal processingand signal analysis. In another arrangement, data acquisition card 120may include all or a portion of signal processing means 230, allowingsampling, digitizing and processing of analog signal 115 to be performedon data acquisition card 120. An example of such an integrated PCMCIAcard is the Bullet_(dsp) card marketed by Communication Automation andControl, Inc. The Bullet_(dsp) card is described in a data sheetentitled “PCMCIA TI TMS320C32,” published by Communication Automationand Control, Inc., the disclosure of which is incorporated herein byreference.

[0034] Signal processing means 230 performs digital signal processing oftime domain digital signal 125 received from data acquisition card 120.Typically, signal processing means 230 is implemented in conventionalmodular software blocks, which may be selected and combined to performvarious processing functions, as further illustrated in FIG. 3. Thissoftware may implement functions such as filtering, fast Fouriertransform, integration or averaging, which may be selected and arrangedas desired.

[0035] Signal analyzing means 240 typically is software that examinesprocessed digital signals received from signal processing means 230 andproduces predictive maintenance information. Upon commands receivedthrough operating system 200, signal analyzing means 240 conductsanalyses such as trend analysis, alarm detection, spectral analysis,data plotting or report generation. An example of signal analyzing means240 is the analysis software incorporated in Entek ScientificCorporation's EMONITOR® for Windows, as described in Chapters 7, 9, 10and 11 of “EMONITOR® for Windows User's Guide, Second Edition 1994,”Manual No. EEW0002B.

[0036] Referring now to FIG. 3, a software block diagram illustratessignal processing software for implementing signal processing means 230which includes modular processing elements 310 a-310 d which may beselected and combined as required. It will be understood by thoseskilled in the art that other arrangements of signal processing elementsmay be used with the present invention. In addition, it will beunderstood by those skilled in the art that other non-modular signalprocessing software techniques may be used with the present invention.

[0037] Referring now to FIG. 4, an electrical block diagram illustratespower supply 150 for accelerometer 160. Power supply housing 410encloses accelerometer battery power supply 420. Accelerometer batterypower supply 420 provides sufficient power to excite an externalaccelerometer. Output means 430 electrically and mechanically couplesaccelerometer battery power supply 420 to an external accelerometer.Typically, output means 430 will include an MS-3106 connector commonlyused in accelerometer applications, but it will be understood by thoseskilled in the art that other structures may be used with the presentinvention, including coaxial and other types of standard connectors.

[0038] Input means 440 electrically and mechanically couplesaccelerometer battery power supply 420 to an external device, such as anA/D converter, and receives control signal 450 from the external device.Accelerometer battery power supply 420 may be responsive to controlsignal 450, deactivating power output to the external accelerometer inthe absence of control signal 450, thus offering the capability tominimize power consumption during non-measurement periods and extendingbattery life or time between recharges.

[0039]FIG. 4 shows accelerometer battery power supply 420 furtherincluding battery 422, charging means 424, and regulating means 426.Charging means 424 provides the capability to charge battery 422.Regulating means 426 takes the power output from battery 422 andprovides the voltage and current conditioning required to excite theexternal accelerometer. It will be understood by those skilled in theart that not all of these elements are required for all embodiments ofthe present invention. Different power supply configurations may, forexample, utilize disposable or removable batteries and eliminate theneed for internal charging means 424.

[0040]FIG. 5a illustrates operations for measuring and collectingvibration data from machines, implemented in a battery-operated poweredcomputer. First, in Block 510 a user selects a machine identificationfor measurement. In Block 520 a time domain accelerometer signal 515 isprocessed to produce a digital signal 525. In Block 530 the digitalsignal is analyzed to produce predictive maintenance information, suchas detection of alarm conditions due to vibration magnitudes exceedingpredetermined limits or reports concerning machine vibration parameters.Referring to FIG. 5b, in an alternate embodiment, the operations ofBlock 520 may be preceded by a step of sampling and digitizing an analogtime domain accelerometer signal to produce a time domain digitalaccelerometer signal 516, as shown in Block 511. In addition, predictivemaintenance information 526 may then be displayed, as shown in Block540.

[0041]FIGS. 6a-6 b illustrate the selection step of Block 510 of FIGS.5a-5 b in greater detail. In FIG. 6a the user enters a data collectionwindow 600 in which he may select a machine identification formeasurement, as shown at 601. The display informs the user of theidentification selected, which typically is a location on a particularmachine, as shown at 602. The user typically commands data acquisitionby selection of an icon, as shown at 603.

[0042] The parameters associated with a particular machineidentification typically have been previously entered into a database.This may be done manually, as shown in FIG. 6b. Within a data entrywindow 610, the user selects a desired machine identification, asillustrated at 611, and enters the associated parameters, as shown at612. Alternatively, parameters may be entered with the aid ofpredetermined machine templates, as shown in FIG. 6c. These parametersmay include signal processing parameters for use in the processing stepof Block 520 of FIG. 5, but it will be understood by those skilled inart that other arrangements may be used with the present invention, suchas allowing the user to select particular signal processing parameterswhile in data collection window 600.

[0043]FIG. 7 illustrates the signal analyzing operation of Block 530 ofFIG. 5, specifically the displayed results of a spectrum analysis. Itwill be understood by those skilled in the art that other analyses maybe performed on digital signals, such as magnitude or crest factorcalculations or detection of alarm conditions.

[0044]FIG. 8 illustrates the data collection system of the presentinvention further including transmission of machine identifications,measurement parameters, time domain accelerometer signals, frequencydomain digital signals and predictive maintenance information to othercomputers 820 a-820 n linked to the battery operated portable computer110 by means of a network 810. It will be understood by those skilled inthe art that network 810 may be hardwired or may employ radio frequency(RF) or other communications links. Under this aspect of the invention,machine-related data may be uploaded from the battery powered portablecomputer 110 to computers 820 a-820 n for subsequent data management,processing, analysis or display.

[0045] In the drawings and specification, there have been disclosedtypical preferred embodiments of the invention and, although specificterms are employed, they are used in a generic and descriptive senseonly and not for purposes of limitation, the scope of the inventionbeing set forth in the following claims.

That which is claimed:
 1. A data collection system for measuring andcollecting vibration data from machines, said data collection systemcomprising: an accelerometer including a motion sensitive transducer, anaccelerometer output and means for coupling said motion sensitivetransducer to a machine to produce an analog signal at saidaccelerometer output; a data acquisition card having an analog input anda digital output, said accelerometer output being electrically coupledto said analog input, said data acquisition card sampling and digitizingsaid analog signal to produce a time domain digital signal at saiddigital output; a battery powered portable computer including anexpansion slot, said data acquisition card digital output beingelectrically and mechanically connected to said expansion slot, saidbattery powered portable computer further comprising: a databaseincluding a plurality of machine identifications and associatedmeasurement parameters; user input means for user selection of a machineidentification for measurement; and signal processing means, forprocessing said time domain digital signal according to the measurementparameters associated with the selected machine identification.
 2. Adata collection system according to claim 1 wherein said signalprocessing means comprises means for processing said time domain digitalsignal to produce a frequency domain digital signal; said batterypowered portable computer further comprising signal analyzing means foranalyzing said frequency domain signal to produce predictive maintenanceinformation.
 3. A data collection system according to claim 1 furthercomprising means for transmitting at least one of said machineidentifications, said measurement parameters, said time domain digitalsignal and the processed time domain digital signal to a secondcomputer.
 4. A data collection system according to claim 2 furthercomprising means for transmitting at least one of said machineidentifications, said measurement parameters, said time domain digitalsignal, said frequency domain digital signal and said predictivemaintenance information to a second computer.
 5. A data collectionsystem according to claim 1 further comprising means for displaying atleast one of said machine identifications, said measurement parameters,said time domain digital signal and the processed time digital domainsignal.
 6. A data collection system according to claim 2 furthercomprising means for displaying at least one of said machineidentifications, said measurement parameters, said time domain digitalsignal, said frequency domain digital signal and said predictivemaintenance information.
 7. A data collection system according to claim1 further comprising power supplying means, for supplying power to saidaccelerometer.
 8. A data collection system according to claim 7 whereinsaid power supplying means electrically and mechanically couples saidaccelerometer output to said data acquisition card analog input.
 9. Adata collection system according to claim 8 wherein said power supplyingmeans is responsive to said data acquisition card, for supplying powerto said accelerometer when said data acquisition card is activated. 10.A data collection system according to claim 1 wherein said signalprocessing means comprises software modules which execute on saidportable computer.
 11. A data collection system according to claim 1wherein said data acquisition card is a PCMCIA data acquisition card.12. A data collection system according to claim 1 wherein said dataacquisition card is a sound card.
 13. A data collection method formeasuring and collecting vibration data from machines, said datacollection method comprising the following steps which are all performedin a portable battery powered computer: allowing user selection of amachine identification for measurement; processing said time domainaccelerometer signal according to measurement parameters associated withthe selected machine identification to produce a digital signal; andanalyzing said digital signal to produce predictive maintenanceinformation.
 14. A data collection method according to claim 13 whereinsaid processing step is preceded by the step of: sampling and digitizingan analog accelerometer signal to produce the time domain accelerometersignal.
 15. A data collection method according to claim 13 furthercomprising the step of transmitting at least one of said machineidentifications, said measurement parameters, said time domainaccelerometer signal, said frequency domain digital signal and saidpredictive maintenance information to a second computer.
 16. A datacollection method according to claim 13 further comprising the step ofdisplaying at least one of said machine identifications, saidmeasurement parameters, said time domain accelerometer signal, saidfrequency domain digital signal and said predictive maintenanceinformation.
 17. A data collection method according to claim 13 whereinsaid digital signal is a frequency domain digital signal.